Biomedical subjects

Luiz Lavinsky

Publications and source records attributed to Luiz Lavinsky.

8 recordsLinked to original sources

PubMed2006

Morphometric study of the external and middle ear anatomy in sheep: a possible model for ear experiments.

Sheep are a potentially useful model for otologic surgical training and experimentation, currently limited by the scarcity of morphological comparisons between the structure of the ear in sheep and in humans. A detailed morphometric study of the ear in sheep was carried out using computed tomography. Measurements made with AutoCAD Release 14 were compared with measurements for the human ear reported in the literature. In general, ear structures in sheep are two-thirds the size of those in humans. The important anatomical similarities found in this study between the ear in sheep and in humans suggest that sheep may be a useful model for surgical training and experimentation in some middle ear procedures.

Animals↗

PubMed2006

Postural adaptation in elderly patients with instability and risk of falling after balance training using a virtual-reality system.

Our aim in this study was to assess postural control adaptation quantitatively in unsteady elderly patients at risk of falls in open spaces and given balance training with a virtual-reality system reproducing environmental stimulation. Using a balance rehabilitation unit based on a virtual-reality system that changes sensory information (visual, vestibular, and somatosensory), we treated 26 elderly, unsteady patients who were prone to falling (age range, 73-82 years) and who were enrolled in a customized vestibular rehabilitation program. We assessed postural responses by posturography before and after 6 weeks in the vestibular rehabilitation program under two conditions: (1) standing, eyes open, static visual field, and (2) standing, eyes open, dynamic visual field through virtual-reality goggles, generating horizontal optokinetic stimulation (70 degrees per second angular velocity). We recorded postural responses with a platform measuring the confidential ellipse of the center-of-pressure distribution area and sway velocity with a scalogram analyzing postural behavior by wavelets. After 6 weeks of treatment, postural response confidential ellipse and sway velocity values were lower, evincing decreased amplitudes and sway frequency contents in the scalogram by wavelet under both stimulation paradigm conditions. These findings suggest postural adaptation under the two perceptual conditions when patients had static and dynamic visual fields. The possibility of treating elderly fallers with balance disorders using a virtual-reality environmental stimulation reproduction system is discussed.

Accidental Falls↗

PubMed2005

Glucose and insulin profiles and their correlations in Ménière's disease.

Changes in carbohydrate metabolism, admittedly one of the most prevalent etiologies of Méière's syndrome, can be diagnosed early by 5-hour glucose and insulin curves with a 100-g glucose load, a test more sensitive than those traditionally used in investigating impaired glucose tolerance or diabetes mellitus. This study investigated carbohydrate metabolism characteristics in 64 patients with typical Ménière's disease. We demonstrated that 72% of them had some variable degree of hyperinsulinemia as shown by their plasma insulin curves, whereas alterations on the glucose curve (reactive hypoglycemia or hyperglycemia) were found for only 21%. More advanced hyperinsulinemic conditions (i.e., glucose intolerance or diabetes mellitus) were usually associated with changes in lipid profiles and with a central pattern of fat distribution and systemic hypertension. We found a very strong correlation between insulin concentrations measured by chemoluminescence and by radioimmunoassay; the latter, however, showed values 1.3 times higher than those measured by chemoluminescence. These findings confirm the need to include 5-hour glucose and insulin curves in the diagnostic routine when investigating Ménière's disease. In that way, an early diagnosis of hyperinsulinemia, the metabolic change most often involved in the pathogenesis of cochleovestibular disorders, can be made.

Body Mass Index↗

PubMed2004

Hyperinsulinemia and tinnitus: a historical cohort.

Tinnitus affects millions of people worldwide, and it signals the presence of several underlying diseases, including hyperinsulinemia. The aim of this study was to evaluate the response to dietary treatment in 80 patients with associated tinnitus and hyperinsulinemia. On the basis of data obtained by a questionnaire, two groups were established: One included patients who followed the prescribed diet; the other group included patients who did not comply with the treatment. The likelihood of improving tinnitus symptoms was fivefold higher in hyperinsulinemic patients who followed the diet than in those who did not (relative risk [RR], 5.34; 95% confidence interval [CI], 1.85-15.37; p < .05). In addition, resolution of tinnitus was reported by 15% of the patients who followed the diet as compared to 0% of those who did not. These findings underscore the importance of including hyperinsulinemia in the routine diagnostic investigation of patients with tinnitus regardless of whether associated with neurosensory dysacusis or vertigo (or both).

Case-Control Studies↗

PubMed2003

An ELISA serum assay for autoantibodies to HSP70 in immune-mediated hearing loss.

A Western blot to detect anti-HSP70 autoantibodies has been reported to be of diagnostic value for immune-mediated hearing loss patients. While setting up this Western blot in our lab, we detected two main problems. First, some patients were positive for antibodies to a 70-kDa protein when tested against a whole cell lysate, but negative if the antigen used was purified HSP70. Second, if high amounts of purified HSP70 were loaded on the gel, both patients and healthy controls were positive. We have developed and optimized an ELISA as an alternative to the Western blot. This assay is more appropriate to identify positive and negative individuals because it is semi-quantitative. The ELISA is also more sensitive, requiring very low concentrations of the antigen and thus minimizing false positives. Finally, we demonstrated that immune-mediated hearing loss patients recognize mainly the native form of HSP70, a fact that potentially leads to false negatives when a denaturing Western blot assay is used for diagnosis. To test the diagnostic value of the ELISA, we performed a blind test with 70 hearing loss patients, as well as 30 healthy controls. A sensitivity of 84% and a specificity of 93% were obtained, superior to what has been reported so far for the Western blot.

Adolescent↗

PubMed2002

Otitis media in children: seasonal changes and socioeconomic level.

OBJECTIVE: Our objective was to determine the frequency of otitis media (OM) in relation to socioeconomic and seasonal factors in a city in southern Brazil. METHODS: A prospective, longitudinal study was carried out with a 3-4-year-old cohort of children randomly selected in schools serving populations of higher socioeconomic status (AB; monthly family income >10 minimum wages, US$ 1000) or lower socioeconomic status (CD; monthly family income < or = 3 minimum wages, US$ 300). The children were assessed in the fall, winter, and spring of 1997 using otoscopy and tympanometry. RESULTS: Among 156 children who finished the study, 53.8% belonged to socioeconomic group CD. Otoscopy suggested chronic suppurative otitis media (OM) (tympanic membrane perforation or otorrhea) in <6% of children in the CD group, with no seasonal variation. Alterations suggesting secretory otitis media (SOM) were significantly more frequent in the CD group (P< or = 0.001), with a peak in the winter. The prevalence of SOM on otoscopy was: fall (20.9% AB; 38.1% CD); winter (28.6% AB; 81% CD), and spring (23% AB; 49.3% CD). The incidence of SOM in the winter according to tympanometry was 18.4% (group AB) and 72.9% (group CD). Among children with a normal tympanogram in the fall, 44.7% presented a type B tympanogram (presence of middle ear effusion) in the winter. Only 17.6% still presented a type B tympanogram in the spring. From the ears with type B tympanogram in the fall, 80% had the same result in the winter, and 60.9%, in the spring. A sharp seasonal SOM peak was observed in the CD group in the winter. CONCLUSION: Children in the lower socioeconomic group have a peak incidence of serous otitis media (OM) in the winter. Presence of type B tympanogram in the fall and belonging to socioeconomic group CD are indicators of poor prognosis in terms of the spontaneous resolution of SOM.

Acoustic Impedance Tests↗

PubMedDate not supplied

CT-Scan sheep and human inner ear morphometric comparison.

INTRODUCTION: Studies about the use of sheep in surgical training and experimental otologic surgery are rare. This study intends to contribute to the knowledge on this field. AIM: To study sheep inner ear structures using computerized tomography and serial cross-sections to collect more accurate morphometric data to compare sheep and human ears. MATERIAL AND METHODS: This descriptive study compared the inner structures of sheep and human ears. Measurements were made using computerized tomography, and they were stored in a DICOM compact disc for later analysis and manipulation, with a program used for medical image analysis (Osíris 4.16). RESULTS: Mean measures for sheep and human ears were found to be similar in this morphological study. Most structures (10 out of 15) maintained the 2/3 ratio of sheep to human ear. CONCLUSION: The results of this morphometric study of sheep ear are an important contribution to the development of an animal model to be used for surgical training and experimental otologic surgeries.

Animals↗

PubMedDate not supplied

[Prevalence of hearing loss in very low birth weight neonates].

OBJECTIVE: To evaluate the prevalence of hearing alterations in very low birth weight patients in the Neonatal Intensive Care Unit of the Hospital de Clínicas de Porto Alegre and to study the variables that can be related to alterations of the hearing acuity. METHODS: A transversal study was carried out. The study included all very low birth weight neonates admitted to the Neonatal Intensive Care Unit of the Hospital de Clínicas de Porto Alegre from September 1, 2000 to January 31, 2002. All patients were submitted to distortion product otoacoustic emission tests at hospital discharge. When the test showed alterations, it was repeated 30 days later. However, when the same patient presented otoacoustic emission alterations in both tests, he/she was submitted to the auditory brain response testing. The result of this test was considered abnormal from 35 dB NA. RESULTS: We studied 96 neonates. Six children presented alteration in the distortion product otoacoustic emission test as well as in the auditory brain response test. Children's mean age was 31.5 +/- 2.6 weeks, their birthweight was between 640 g and 1,500 g, and 57.3% of the patients were female. The gestational age and the Apgar score of 5 minutes were inferior in the group presenting abnormal results of otoacoustic emission and auditory brain response tests compared to the other groups, reaching bordering significance. All the remaining aspects investigated did not present any statistically significant difference. CONCLUSIONS: The prevalence of hearing loss in the very low birth weight neonates cared for at the Neonatal Intensive Care Unit of the HCPA was 6.3%, and bordering significance associations related to gestational age and 5 minutes Apgar score were observed.

Cross-Sectional Studies↗